Organic tertiary phosphines



United States Patent 3,116,317 ORGANIC TERTIARY PHGSPHINES MartinGrayson, Norwallr, and Patricia A. Keough, Ridgefield, Conn, assignorsto American Cyanamid Company, New York, N.Y., a corporation of Maine NoDrawing. Filed May 25, 1960, Ser. No. 31,517 4 Claims. (Cl. 260--465.1)

This invention relates to organophosphorus compounds and to thepreparation thereof. More particularly, the instant discovery concernsorganic tertiary phosphines corresponding to the general formula whereinP represents phosphorus; A is a beta-substituted ethyl functionalmoiety, including NCCH CH in which R is H or an alkyl group having 1 to6 carbon atoms, and R is an alkyl group having 1 to 6 carbon atoms, saidB-substituted ethyl functional group being attached directly to Pthrough its wcarbon atom; Z is a substituted and unsubstituted, branchedand straight chain alkyl group; a substituted and unsubstituted,branched and straight chain alkenyl group; a substituted andunsubstituted cycloalkyl group; a substituted and unsubstitutedcycloalkenyl group; said substituted alkyl, alkenyl, cycloalkyl andcycloalkenyl groups having their substituents on a carbon atom at leastthree carbon atoms removed from the phosphorus atom; and n represents avalue from 1 to 3.

According to the present invention, the tertiary phosphines contemplatedherein are prepared by a process which comprises contacting a compoundof the formula in which A, P, Z and n have the meanings given above,with a halogen-substituted compound having the formula ZX, wherein Z isthe same as above and X is a halogen atom, including bromine, chlorineand iodine, to produce the corresponding quaternary phosphonium halidehaving the structure The quaternary phosphonium halide is reacted with astrong base, such as a metal alkoxide, sodium cyanide, and sodium amide,and a product corresponding to the foris recovered. In all the formulaethe symbols have the significance attributed to them hereinabove.

Reaction of the quaternary phosphonium halide with a strong base may becarried out in the presence of an inert organic solvent, such as analcohol, liquid ammonia, and the like. For example, when a metalalkoxide, such as sodium methoxide, is used as the base, a solvent suchas methanol may be used as a reaction medium. Likewise, liquid ammoniamay be employed as the solvent when sodium amide, for example, is thebase reactant.

A typical reaction according to the instant invention involves reactingtris (2-cyanocthyl)phosphine with methyl iodide to produce thecorresponding quaternary phosphonium iodide having the formula Thethus-produced quaternary phosphonium iodide may then be reacted withsodium ethoxide to yield:

"ice- The molar ratio of ZX to (A),,P(Z) contemplated herein is at least1, preferably slightly greater than 1, say, up to about 10. However, aratio substantially greater than 10, on the order of or more, may beused.

While an equimolar concentration of quaternary phosphonium halide andbase reactant is suitable, it is by no means critical, sinceconcentration ratios of 25:1 or mrlire and 1:25 or less may be used withsatisfactory resu ts.

In general, reaction between a monohalogen-substituted compound and anorganic tertiary phosphine, as contemplated herein, is carried out at atemperature in the range of about 0 C. to about 150 C., preferably 15 C.to C. If desired, this reaction may be made to take place in thepresence of an inert solvent, such as glacial acetic acid, an alcohol,acetonitrile, acetone, and the like, in which case the maximum practicaltemperature is preferably that of the reflux temperature of the solvent,as will be seen hereinafter.

With respect to the reaction between the intermediate quaternaryphosphonium halide and the strong base, a reaction temperature in therange of about 5 C. to about 115 C. is employed, preferably 20 C. to 80C.

Although reaction between a tertiary phosphine of the type contemplatedherein having the formula with a monohalogen-substituted compound havingthe formula ZX is generally carried out at atmospheric pressure,sub-atmospheric and super-atmospheric pressures are suitable. The sameapplies to the reaction between the quaternary phosphonium halide andthe strong base.

Among the strong bases contemplated for use herein are the oxides,hydroxides, lower alkoxides, carbonates, cyanides and amides of alkalimetals and alkaline earth metals (including aluminum). Typical are:sodium methoxide, potassium ethoxide, aluminum isopropoxide, sodiumhydroxide, sodium amide, sodium cyanide, sodium carbonate, sodiumbicarbonate, calcium oxide, barium oxide. Other bases within the purviewof the instant discovery are tertiary alkyl amines, tertiary aralkylamines and tertiary heterocyclic amines, such as triethylamines,N,N-dimethylaniline, pyridine, quinoline, heptamethylguanidine, andother similar strongly basic organic tertiary amines.

The present invention will best be understood by reference to thefollowing examples:

EXAMPLE I Methyl Bis(2-Cyan0ethyl Phosphine CH P (CH CH CN) 2 Tris(2cyanoethyl)phosphine (386.4 grams, 2.0 moles) is dissolved in fiveliters of warm (40 C.) glacial acetic acid. Approximately 670 grams(4.65 moles) of methyl iodide is added during a period of 5 minutes withprovision for some external cooling to maintain a temperature of 4045 C.Subsequently, the resulting reaction mixture is stored at roomtemperature (21 C.23 C.) overnight. Solids thus produced are thenremoved from the mixture by filtration and dried to recover methyltris(2- cyanoethyl)phosphonium iodide having a melting point of 239C.240 C.

Sodium niethoxide (70.5 grams, 1.31 moles) is dissolved in 750milliliters of absolute methanol and the resulting solution added to arefluxing mixture of 438 gnams (1.31 moles) of the methyltris(2-cyanoethyl) phosphonium iodide produced above in 750 millilitersof methanol. After two hours of refluxing at about 65 C. the methanol isstripped under vacuum (10 millimeters pressure and 50 C.) from thereaction mixture, 600 milliliters of water is added and the resultingmixture extracted with 300 milliliters of benzene in three substantiallyequal portions. The benzene extraction solution is then dried at 21C.-23 C. With magnesium sulfate and stripped under vacuum (0.25millimeter pressure and 50 C.) to remove the benzene solvent andderivative Z-methox-y-propionitrile having a boiling point less thanabout 27 C. at 0.25 millimeter pressure. The residual liquid methylbis(Z-cyanoethyDphosphine distills at 159 C.160 C. (0.35 millimeterpressure), weighs 116.5 grams, and has a refractive index of 11 1.5030.Analysis.Calculated for -C7H11N2P is 20.09 percent P; 19.88 percent P isfound.

EXAMPLE II Methyl Ethyl Z-C'yanoethyl Phosphine CH3PCH2CH2CN CHzOHsMethyl bis-(2-cyanoethy1)phosphine (23.0 grams, 0.15 mole) produced asin Example I, above, is dissolved in 75 milliliters of absolute ethanolat room temperature (21 C.23 C.), and 52 grams (0.33 mole) of ethyliodide is added. The mixture is refluxed (about 80 C.) for 15 minutes,cooled to room temperature (21 C.- 23 C.) and the resulting solidfiltered therefrom and dried under vacuum (0.25 millimeter pressure, 21C.-23 C.). The product methyl ethyl bis(Z-cyanoethyDphosphonium iodideweighs 35.5 grams and has a melting point of 210 C.211 C. Iodideanalysis is 41.2 percent (oaculated 40.9 percent).

Sodium metal (2.3 grams, 0.10 gram atom) is dissolved in 150 millilitersof absolute ethanol and 31.0 grams (0.10 mole) of methyl ethylbis(2-cyanoethyl) phosphonium iodide (solid) is added thereto. Theresulting mixture is heated to about 60 C. to dissolve the solid and theexcess alcohol evaporated under vacuum conditions (10 millimeterspressure, 50 C.). A paste remains which is extracted with three equal100-milliliter portions of benzene, thus leaving a benzene solutionwhich is stripped of its benzene under vacuum (2.0 milliliters pressure,25 C.) and distilled to yield 7.2 grams of product methyl ethyl2-cyanoethyl phosphine having a boiling point of 68 C.-71 C. at 1.8millimeters of mercury pressure and having a refractive index of n1.4688. Analysis.alculated for C H NP is 23.98 percent P and 23.63percent P is found.

EXAMPLE III Allyl Bis (2-C'yanoethyl)Ph0sphine CH CHCH P (CH CH CN) 2Tris(2-cyanoethyl)phosphine (145 grams, 0.75 mole) is dissolved in 750milliliters of refluxing n butanol and 168 grams (1.0 mole) of3-iodopropene(allyl iodide) is added slowly to the refluxing material.The resulting mixture is refluxed at about 110 C. for an hour afteraddition is complete. After cooling slowly to room temperature (21 C.24C.) the solid found in the resulting reaction mixture is filtered anddried under vacuum, Weighs 240 grams and has a melting point of 177 C.178 C. and is identified as allyl tris(2cyanoethyl)phosphonium iodide.

Sodium metal (4.6 grams, 0.20 mole) is dissolved in 150 milliliters ofabsolute ethanol and 69.4 grams (0.20 mole) of the allyltris(2-cyanoethyl)phosphonium iodide produced above is added. Theresulting mixture is heated to reflux, cooled to room temperature andthe alcohol content thereof removed under vacuum. Water is then added tothe mixture and the aqueous product extracted with chloroform. Thechloroform extract is dried at room temperature with calcium sulfate andthen the chloroform removed by vacuum stripping (50 C., 2 millimeterspressure) to yield 17.5 grams of liquid allyl bis(2- cyanoethyDphosphinehaving a boiling point of 178 C.- 179 C. at 1.65 millimeters pressureand a refractive index of 11 1.4980. Analysis.Calculated for C H N P is4 C, 59.98 percent and H, 7.27 percent; and found C, 59.53 percent andH, 7.75 percent.

EXAMPLE IV Cyclopentyl Bis(2-Cyanoethyl)Phosphine CH2CHz CH-P(CHzOHzCN)z CHz-CH:

Tris(Z-cyanoethyDphosphine (48.3 grams, 0.25 mole) is dissolved in 250milliliters of refluxing butanol and 37.2 grams (0.25 mole) ofbromocyclopentane is added to the refluxing material. After refluxingovernight, the solution mixture is cooled to room temperature (21 C.- 23C.) and the resulting solid cyclopentyl tris(2-cyanoethyl)phosphoniumbromide filtered and dried under vacuum (0.25 millimeter pressure, 21C.-23 vC.) yielding 79 grams of material having a melting point of 83C.- 84 C.

Sodium metal (4.6 grams, 0.2 gram atom) is dissolved in milliliters ofabsolute ethanol and added to 68.4 grams (0.2 mole) of the cyclopentyltris(2-cyanoethyl) phosphonium bromide produced above in 100 millilitersof refluxing absolute ethanol. The alcohol is then stripped therefromunder vacuum, a small amount of Water is added to the resulting materialwhich is subsequently extnacted with three 100-milliliter portions ofchloroform. Next, water is removed from the extraction by drying withcalcium sulfate at 21 C.23 C., and the chloroform is removed undervacuum, leaving 12.5 grams of liquid cyclopentylbis(2-cyanoethyl)phosphine having a boiling point of 165 C.169 C. and arefractive index (11 1.4962. Calculated for C11H17N2P is P, 14.54percent; and found is P, 14.68 percent.

EXAMPLE V Dodecyl Bis(2-Carbeth0xyethyl)Phosphine CH (CH CH P(CH CH COCH CH Tris(2-carbethoxyethyl)phosphine (66.8 grams, 0.20 mole) isreacted with 54 grams (0.20 mole) of l-iodododecane to give thephosphonium salt, dodecyl tris(2- carbethoxyethyl)phosphonium iodide.The phosphonium salt (109 grams, 0.18 mole) thus produced is reacted asin previous examples with 4.15 grams (0.18 gram atom) of sodium metal inabsolute ethanol to give product dodecylbis(2-carbethoxyethyl)phosphine.

EXAMPLE VI 3-M ethyl Butyl Bis (2-Diethylcarbam0ylethyl) Phosphz'ne (CHCHCH CH P [CH CH CON (CH CH 2 Tris(Z-diethylcarbamoylethyl)phosphine(41.5 grams, 0.10 mole) is reacted with 19.8 grams (0.10 mole) of 1-iodo-3-methylbutane to give the phosphonium salt. The resultingphosphonium salt (55 grams, 0.18 mole) is reacted with 4.15 grams (0.18gram atom) of sodium metal in absolute ethanol to give 3-methyl butylbis(2-diethylcarbamoylethyDphosphine which is recovered.

EXAMPLE VII Methyl Ethyl n-Propylphosphine 0 Hg P C Hz 0 H2 C H3 Methylethyl 2-cyanoethyl phosphine prepared as in Example II, above (11.8grams, 0.10 mole), is dissolved in 75 milliliters of absolute ethanol atroom temperature under nitrogen, and 25.5 grams (0.15 mole) of n-propyliodide is added. After 15 minutes of reflux, the solution is cooled, thesolid filtered and dried. The resulting methyl ethyl n-propyl2-cyanoethyl phosphonium iodide (26 grams, 0.09 mole) is added to 2.1grams (0.09 gram atom) of sodium metal dissolved in milliliters ofabsolute ethanol. After refluxing for 15 minutes the reaction mixture isstripped of ethanol by heating at reduced pressure and the productmethyl ethyl n-propyl phosphine is extracted and recovered bydistillation in the usual manner.

EXAMPLE VIII Methyl Z-Cyanoethyl 3-Cyan0pr0pyl Phosphine CHiCIIzON OHS-PCH2CH2CHQCN Methyl bis(2-cyanoethyl)phosphine prepared as in Example I,above (196.5 grams, 1.27 moles), is dissolved in 350 milliliters ofnormal butyl alcohol at 50 C. under a nitrogen atmosphere, and 220.0grams (1.49 moles) of 3-bromobutyronitrile is added in 30 minutes at 115C. or the reflux temperature of the solvent. The reaction temperature isquickly reached by means of the vigorous exothermic nature of thereaction. The reaction is continued over night at 110 C. by applicationof external heat. Upon cooling a solid form which is dried and weighs378.5 grams. Analysis for bromide is 26.10 percent; calculatedtheoretical value is 26.44 percent.

A solution of 27.6 grams (1.20 gram atoms) of sodium metal in 750milliliters of absolute ethanol is dropped over a period of 30 minutesinto a refluxing, stirred slurry of 362.7 grams (1.20 moles) of methylbis(2-cyanoethyl)3- cyanopropylphosphonium bromide in 500 milliliters ofabsolute ethanol under a nitrogen atmosphere. After an additional 30minutes of refluxing, the solution is cooled and filtered to removesodium bromide. After concentration by warming and pumping at millimeterpressure, the residual liquid is filtered and distilled at 1.5millimeter pressure. The product has a boiling point of 175 C. and arefractive index of n 1.4995. Analysis calculated for carbon is 57.13percent; hydrogen 7.79 percent. Analysis found for carbon is 57.25percent; hydrogen 7.79 percent.

Unless otherwise indicated, the parts (percentages) specifiedhereinabove are by weight.

Typical of the halides contemplated herein represented by ZX, other thanthose mentioned above, are the halides of isobutyl, S-methyl, l-butyl,2-butyl, 2-cyclohexylethyl, 2-octyl, 2-penty1, 2-propyl, and the like.

Other typical alicyclic groups represented by Z in the formula arecyclohexyl, l-decalyl, 4-methylcyclohexyl, 3-paramenthyl,2-cyclohexenyl, 3-cyclohexenyl, 3-cyclopentenyl, 2-cyclododeceny1, andthe like.

Among other substituted alkyl, alkenyl, cycloalkyl and cycloalkenylgroups represented by Z in the formula said substituents being presenton a carbon atom at least 3 carbon atoms removed from the phosphorousatom, are 3-phenylpropyl; 4-diethylaminobutyl; 8-nitrooctyl; 18hydroxyoctadecyl; S-carbethoxypentyl; 3(N,N-diethylcarbamyl)cyclohexyl;3-carbamoylpropyl; 3-ethoxypropyl; 3-phenoxyhexyl; 4,4-dimethoxybutyl;3-ketocyclopentyl; 3-cyclohexanyl; 4-fluorocyclohexyl; and the like.Obviously, other substituents similar to those just given, such asdi-lower alkyl amino, carboxyalkyl (lower alkyl esters), di-lower alkylcarbamoyl, lower alkyl or phenyl ethers or thioethers, lower aliphaticacetals, halo (e.g. fiuoro, iodo), and the like, are contemplatedherein. These substituted reactants yield the corresponding products.

The novel products of the present invention are useful in polymerizationprocesses designed to give linear phosphorus-containing polymers withmetal bonding and fireretardant properties. For example, the product ofExample I, above, may be combined with formaldehyde to yield thecorresponding bis-nitrile formaldehyde polyamide, a water-soluble film.This film may be cross-linked with hexamethylol melamine to give atough, clear, hard film.

These films have numerous uses, such as in the packaging art forWrapping goods (e.g. clothing, linens, etc.). If desired, cloth may beimpregnated with the watersoluble linear polymers prepared as above fromthe compounds contemplated herein.

The completely unsymmetrical phosphines prepared according to thepresent invention, such as ethylmethyl-Z- cyanoethylphosphine, in theform of their phosphine oxides, are capable of resolution into opticallyactive forms (dextroand levorotatory) which exhibit unusualphysiological activity compared to the unresolved, racemic com pound.

Furthermore, the product organic tertiary phosphines produced accordingto the present invention have direct utility as gasoline additives. Forexample, up to about 10 milliliters of any one of these tertiaryphosphines admixed with one gallon of gasoline affords protectionagainst surface ignition, misfiring, and the like.

The nickel carbonyl derivatives of organic tertiary phosphines, such astributylphosphine [(C H P] Ni(CO) have been shown by Reppe et al. to beuseful as polymerization catalysts. See Reppe et al., Ann. 560 pages104-116 (1948); CA 43, 6202 (1949).

While the present invention has been described in detail with respect tospecific embodiments thereof, it is not intended that these detailsimpose unnecessary limitations upon the scope of the invention, exceptinsofar as these limitations appear in the appended claims.

This application is a continuation-in-part of application S.N. 770,574,filed October 30, 1958, now US. Patent 3,005,013.

We claim:

1. An organic tertiary phosphine corresponding to the formula wherein Arepresents a beta-substituted ethyl functional moiety selected from thegroup consisting of References Cited in the file of this patent UNITEDSTATES PATENTS Stiles et al. Aug. 20, 1957 Grayson et al Oct. 17, 1961UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No, 3116,317 December 81 1963 Martin Grayson et al.

ified that error appears in the above numbered pat- It is hereby certhat the said Letters Patent should read as ent reqiiring correction andt corrected below.

Column 3 line 39 for "milliliters" read millimeters Signed and sealedthis 30th day of June 1964,

(SEAL) Attest:

EDWARD J. BRENNER Commissioner of Patents ERNEST W. SWIDER Aiicsting@fficer

1. AN ORGANIC TERTIARY PHOSPHINE CORRESPONDING TO THE FORMULA